On the page Events, subtab Events, choose an event, in the row, far right side, select the button Select.
On the tab Details, subtab Vendors, select the option +Add Vendor.
In the pop-up window Select the Vendor Type, next to the vendor, select the button SELECT.
In the pop-up window Add the (Vendor), type at least the first three letters of the vendor’s name.
In the pop-up window Add the (Vendor), next to the vendor, select the button SELECT. (If the vendor isn't listed, at the bottom of the pop-up window, invite the vendor to share the event. Select the button INVITE.)
In the pop-up window, Set the Permissions, review and choose from the following options: a. Use default permissions. b. Or select the options Allow all or Allow none. c. Or create custom permissions for each option using the corresponding sliders. d. Select the button INVITE. The vendor receives an invite to collaborate.